Power transmission



` 50 ing portion of the frame are a pair of work position-- Patented Jan. 9, 1940 vUNITED STATES -POWER. TRANSMISSION' Ferris T. Harrington and Rudolf E. Esch, Detroit, Mich., assignors to Vickers Incorporated, Detroit, Mich., a corporation of Michigan 4"PATENT OFFICE n A i Rassen Iv MAY 1.91942' Applicationv netmary z3, lass, serial No. 191,894

11 Claims.`

This invention relates to power transmissions and more particularly to those ofthe fluid type l stroke while the other ram is caused to ascend simultaneously on its return stroke. Machines of this character are frequently provided .with work positioning means which operate to advance and withdraw work holding xtures to and from working position opposite each broaching tool in proper sequence. v

It is an object of the. present invention t'o proj vide a hydraulic power transmission system adapted 'to operate a machine of this character g5 automatically in cycles of predetermined sequence which repeat themselves continuously until the machine is stopped at will.

Another object is to provide a novel method of maintaining the two rams in step by the provision of improved prei-lll means for'the secondary circuit connecting the return ends of the two main rams.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

Figure 1 is a diagrammatic View of a hydraulic power transmission system incorporating a preferred form o f the present-invention.

Figure 2 is a top view of a broaching machine, incorporating the transmission of Fig. 1.

Figure 3 is a front view of the machine shown in Fig. 2.

Referring now to Figures 2 and 3, the broaching machine may comprise a main frame in which are slibably mounted a pairof rams 2 and 3 which are formed as cylinders reciprocable on piston rods 4 and 5. The rams 2 and 3 carrysurface broachtools 6 and 1. Slidably mounted on the table ving slides 8 and 9 which are actuated oppositely by pinions I I and I3 connected to shafts I 5 and I1. The latter are connected by suitable linkage I9 to the under side of the andes s and s. The pinions I I and I3 engage a rack 2| which is connected to a piston rod 23 carryingnp sten 25 Areciprpcable in a work shifting cylinder 1.

Referring to Fig. l tank I0 contains a supply of oil which may be withdrawn through suction conduits I2 and I4, by a pair of pumps I6 and I8 kadapted to be continuously driven by a suitable prime mover, such as an electric motor, not

shown. l

- The pump I6 has a delivery conduit 20 in which a conventionalrelief valve 22 is inserted 'foL bypassing oil through a conduit 24 to the tank whfnever a predetermined pressure is exceeded in the conduit 20. The conduit 20 extends to the pressure port of a'solenoid operated, spring centered,

open center, four-way valve 26. The latter has its tank ports connected to tank by a conduit 28 and its cylinderports connected to the opposite ends of cylinder 21 by conduits 30 and 32. f

The pump I8 has a delivery conduit 34 in which is inserted a conventional relief valve 36 for bypassing oil to the tank through a conduit 38 whenever a predetermined pressure is exceeded in the l conduit 34. The conduit 34 extends to the pressure port of a. solenoid operated, spring centered, open center, four-way valve 40, having its tanks port connected to tank by a conduit 42. The cylinder ports of the valve 40 are connected to the head ends of the cylinders 2 and 3 by conduits 44 and 46 respectively. A f

The rod ends of the cylinders 2 ald 3 are connected together in a secondary circuit by conduits 48 and 50 which also communicate with a conduit 52 which extends to one cylinder port of a spring centered, closed center, four-way valve 54. The pressure port of the valve 54' is lconnected to the discharge conduit 34 of pump I8 by a. conduit 56 while the tank ports are con-l nected to tank by a conduit 58. The other cylinder port of valve 54 is plugged. AFrom the discharge conduit 34, a branch conduit 60 extends through a check valve 62 to a hydrostatic flow control valve 64 which is operable to maintain a constant but adjustable rate of now therethrough in a manner well known in the art. From the valve 64, a conduit 66 extends" to a relief valve 68 adapted to by-pass oil to the tank through a conduit 10 whenever a predetermined pressure is exceeded in the conduit 66. From the relief valve 68 the conduit 66 extends to the conduit 52 of the secondary system. y

Foi' the purpose of controlling the solenoid valves 26 and 40, van electrical circuit is provided as follows: v l

A push button starting switch 65, normally open, connects one side of a suitable power line Ll by conductor 61 Ato the operating coil o! a to a normally closed push lbutton stop Switchs |00, and thence by a conductor |02 to the upper A reaches its upward limit of movement. A conductor 92 extends from switch 88 to a double circuit limit switch 94 adapted to close circuit 82 by a cam 96 on cylinder 3 at its lower limit of travel. From switch 94 a conductor 98 extends solenoid of a four-way valve 26 and to line L2.

Branch conductor 84 leads to a single circuit limit switch |04 adaptedto be closed by acam thence to line L2.

|06 on rod of piston 25 whenever the latter is in its lowermost position. A conductor |88 connects to a conductor which leads to a double circuit limit switch ||2 adapted to be opened by cam 96 on cylinder 3 in its uppermost position. A conductor ||4 extends from switch ||2 to the right hand solenoid of four-way valve` 40 and A conductor ||6 leads oi! or conductor 4 and extends to limit switch ||8 which is adapted to be opened by cam 90 on cylinder 2 at its lowest limit of travel. From there a. conductor extends to conductors |08 and ||0 completing the circuit. A conductor |2| extends from conductor 84 to a limit switch |22 which is adapted to be closed by cam |06 on the rod of piston when the latter is at vits upper limit of travel. A conductor |24 extends to limit switch connects by a conductor |26 to left hand solenoid of fo'ureway valve 40 and -thence to line L2. A conductor |28 extends from conductor |26 to limit switch 94, which will close when cylinder 3 rises. A conductor |30 connects limit switch 94 to conductor |24.

From relay 69, conductor 80, conductor 82 also connects to limit switch I8, which will be closed when cylinder 2 has descended. From limit switch ||8, a conductor |32 extends to limit switch I I2 which is closed by rising of cylinder 3.` A conductor |34 extends from switch |'|2 to push button stop switch |00, from which a conductor |36 extends to the lower solenoid of fourway valve 26 and'thence to line L2. From conductor |34, a. conductor |38 extends to stop Vswitch |00 whence conductor |40 connects to a conductor |42 and operating coil of relay 14.

In operation with pumps |6 and |8 running and with the starting switch open the solenoids of valves 40 and 26 are deenergized,permitting the valves to spring center and by-pass discharge of the pumps. Starting with the parts in the position shown in the drawings, in which theslide 8 is in working position and the cylinder 2 'is ready to start a downward working strokewhile the slide 9 is retracted for reloading and the cylinder 3 has completed a. working stroke,

it will be seen that when starting switch 65- is .l

conduit 20 of the pump |6 tothe conduit 30,

- admitting pressure oil-to the upper end of cylinconductor |36.

andere der 21 and holding the piston 25 in its lowermostpositionaslongasthecamsand88 engage the limit switches 88 and 84. A circuit is also established to the right hand solenoid of valve 40 through the relay 89, conductor 80, conductor 84, switch |04, conductor |08, conductor ||0, switch 2 and conductor |I4. Valve 4l is accordingly shifted to the right to connect the Y pressure port with conduit 44.

inder 2. As the cylinder 2 reaches the bottom o! its stroke and cylinder 3 reaches the top of its stroke, limit switches ||8 and I2 are depressed thus establishing a circuit to the lower solenoid of valve 26.E This circuit is through relay 68. conductor 80, conductor 82, switch ||8, conductor |32, switch H2, conductor |34, switch |00 and Valve 26, accordingly, moves downwardly, connecting pressure oil to the conduit 32 and causing the piston 25 to move upwardly, retracting the slide 8 and advancing the slide 9. The shifting of both limit switches ||2 and ||8 also opened the circuit to the right hand solenoid of valve 40, permitting the latter to spring center and by-pass the pump |8.

As the piston 25 reaches its upward limit, cam |06 depresses limit switch |22 to establish a circuit to the left hand solenoid of valye 40 through relay 69, conductor 80, conductor 84, conductor |2|, switch |22, conductor |24, switch 88, and conductor |26. -Valve40, accordingly, moves to the left to connect pressure conduit 34 to the conduit 46 to admit pressure oil to the head end of cylinder 3, The latter moves downwardly on a broaching stroke and the foil dis charged from the rod end is delivered to the rod end of cylinder 2 through the secondary circuits 48 and 50, causing cylinder 2 to perform a. return strokes At the start of these movementscf cylvinders 2 and 3, cams 90 and 96 ride otr from limit again establishing a circuit through relay 69,-

conductor 8 0, conductor 82, switch 88, conductor 92, switch 94, conductor 98, switch |00 and conductor |02, to the upper solenoid of valve 26.

'Ihe latter moves upwardly to admit pressure oil from pump |6 to the conduit 30 and causes l piston 25 to move downwardly, reti-acting slide 9 and advancing slide 8. The shifting of both limit switch 88 and 94deenergzes the left hand solenoidfot the valve '40, permitting the latter to spring center and by-pass pumpl8; At the completion of this movement, the parts are restored to the position shown inthe drawings, except that relay 68 remains energized so that v`another cycle takes place immediately and the machine continues in operation through the same cycles, repeatedly. Y.

To stop the machine the push button switch |00 may be depressed. This has the effect of causing the machine to continue in operation until the endor. a broachingstroke is reached either with cylinder 2 down or with cylinder -3 -dowm It willbe seen that with Switch IAII depressedthe rst time thereafter that the line 93 or the line |34 is energized for the purpose of normally energizing solenoid valve 28 to shift the work slides; this energization'is transferred to the relay 14 and opens the same thus opening the holding circuit 'I2-16 of relay 69. The latter accordingly opens preventing further energization of either one of the solenoid.va1ves. Thus the machine may be readily brought to rest at the completion of a working stroke on either side. If it is -necessary to stop the machine immediatel'y as in an emergency the emergency stop switch 18 is depressed thus opening the holding circuit of relay 59 instantly and deenergizing ,both solenoid valves. The latter spring center and by-pass both pumps I6 and I8. The machine is accordingly stopped in whatever position-it may happen to be when the switch 18 is opened. l

For the purpose of insuring replenishing of the secondary circuit to make up for leakage, thev iiow control valve 64 may be adjusted to whatever rate is found suitablefor given operatingl conditions so that the proper quantity of oil from the conduit 34 ows through vthe conduit $0-, check valve 62, ow control 64 and conduits 56 and 52 to the secondary system. The relief valve 68-provides for relieving excessive pressure in the secondary system in case the upgoing cylin-4 der gets to the top before the down-going cylinder gets to the bottom.

It will be noted that either solenoid of valve; 40 remains energized until both of two conditions are fulfilled. The down-going cylinder must reach bottom and the up-going must reach 'top before the solenoid valve 40 c'an be deenergized. The circuit to the right hand solenoid has a e parallel branch portion from conductor II4 through conductor IIG, switch IIB, and conductor |20 to conductor |08 which keeps the solenoid `energized if 'cylinder 3 gets to the top before cylinder 2 gets to the'bottom. Likewise the left" hand ,solenoid circuit has a parallel branch portion from conductor |24 through conductor |30, limit switch 94 and conductor |28 to conductor |26. Thus the pump is never bypassed until bothcylinders have completedtheir strokes. Accordingly, pressure is available either to continue downward movement of one cylinder or to continue upward movement of the other cylinderl through the prefill feed valve 64 whichever may be required.

'Ihe check valve 62 prevents iiow of oil out of the secondary system to the tank through conduit 34 and valve 40 when the latter is in spring centered position. The reset valve 54 may be utilized to manually exhaust oil from the`isecondary system should the same become too full as may happen when adjusting the machine for different set-ups. `'By pulling the plunger valve 54 downwardly, the conduit 52 is connected to tank through conduit 58 thus permitting oil to discharge from the secondary system. Likewise, if it is desired to quickly make up lost fluid in the secondary system, the valve 54 may be pushed upwardly to connect the secondary system to thel pressure conduit 34 through the conduit 58.'

While the form ofembodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood-thatother forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows: 1. In a hydraulic power transmission system 1l the combination of a rstuid motor. a

` uid to operate said motors, electrically operable lone motor or the other fluid motor, pump means for supplying pressure iiuid to operate said motors, electrically operable control means for selectively lay-passing the pump means or causing operation of the first motor ineither direction, electrically operable control 5 means for selectively by-passing the pump means or causing operation of the second motor in either direction, an electric circuit operably .connected to said control means, a manually operable switch for energizing the control means to start operation of the first motor, switch means operated by the iiuid motors for energizing the control means to cause said motors to operate in a predetermined sequence and manually operable means for deenergizing both said control means to cause the pump to be by-passed.

2. In a. hydraulic power transmission system the combination of a iirst uid motor, a second fluid motor, pump means for supplying pressure means for controlling the delivery of id to said motors lindividually, a first pair of limit switches operated by the first motor at opposite ends of its stroke, a second pair of limit switches operated by the second motor at opposite ends of its stroke, a manually controlled switch, an electric circuit connecting the control means and the switches andv arranged when the manual switch is operated to one position to cause repeated operation of said motors through predetermined cycles including aforward stroke of the first motor, a forward stroke of the second motor, a reverse stroke of the first motor and a reverse stroke of the second motor in sequence, andwhen the manual switch is moved to another position to cut off the delivery'of fluid to the motors.

3. In a hydraulic broaching machine of the type having a pair of oppositely movable main slides and an oppositely shiftable work handling member, the combination of a pair of main fluid motors for operating the main slides simultaneously in opposite directions, a second fluid motor for operating the work handling member. a pump for supplying iiuid to the main motors, a second pump for supplying fluid to the second motor, electrically operated control valves for selectively controlling the ow of uid to the motors from their respective pumps, an electric circuit connected to said electrically operated control valves, means for causing operation of said motors 'in repeated predetermined cycles, said means comprising a plurality of limit switches mechanically operated by said motors and connected in said circuit, and a manually operable switclv 'for controlling said circuit independently of the limit switches. l

4. In a hydraulic broaching machine of the type having a pair of oppositely movable main slides, a pair of uid motors for operating the main slides, a pump for supplying uid to operate selectively on a working stroke, means for supplying iiuid to return each motor while) the other is on a working stroke, electrically operated means for controlling the supply of iiuid to the motors on their working stroke, anv electric circuit connected to said control means, and means including limit switches in said circuit for causing operation of said motors in repeated predetermined cycles and ar 1 ranged to prevent initiation of a working stroke lof a motor before both complete return of the same and completion of the working stroke of the other motor.

am s wauwau-anna machine than type having a pair of oppositely movable main slides and an oppositely shiftable work handling member, the combination of a pair of main duid motors for operating the main slides, a second iluid motor for operating the work handling member, a pump for supplying fluid to the main motors to operate one motor or the other selectively on a working stroke, means for supplying fluid to return each main motor while the other is on a working stroke, a second pump for supplying fluid to the second motor, electrically operated control valves for selectively controlling the ilow of iluid to the motors from their respective pumps, an electric circuit connected -to said electrically operated control valves, and means for causing operation of said motors in repeated predetermined cycles said means comprising a plurality of limit switches mechanically operated by said motors and connected to said circuit.v in a manner to prevent operation of the second motor until both motors have completed their respec- .uid into the-secondary circuit continuously at a constant rate'to replace leakage.

7. In a hydraulic broaching mach e of the type having a pair of oppositely movable main,"

slides, a pair oi' piston and cylinder iluid motors for operating the main slides, a pump for supplying iluid to operate one motor or the other selectively on a working stroke, means connecting an end of one cylinder to an end of the other cylinder `to form a secondary circuit for causing the return oi.' one motor during the working stroke of the other motor, and means for bleeding fluid from the pump into the secondary circuit conto replace leakage, said means comprlsing a hydrostatic ilow rate controlling valve connected between the pump outlet and the secondary circuit.

8. Inra hydraulic broaching machine ,of the type having a pair oi oppositely movable main slides, a pair of piston and cylinder iiuid motors for operating the main slides, a pump for supplying iluid to operate one motor or the other selectively on a working stroke. means connecting an end of one cylinder to an end of the other cylinder to form a secondary circuit for causing the return of one motor during the working stroke of the other motor, and means for i'eed- At. ing iluid into the secondary circuit continuously at a constant low rate to replace leakage, and a manually operable valve for at times admitting iluid to the secondary circuit at a high rate.

9. In .a hydraulic power tonV system the combination of a pump, a pair of oppositely movable piston and cylinder fluid motors, means connecting one end ot each cylinder with the pump, means connecting the other ends of the cylinders together in a secondary circuit for causing movement of one cylinder by uid discharged from' the other cylinder and vice versa, control means for selectively directing pressure fluid from the pump to said one end of either cylinder or by-passing the pump operating means for said control means, apilot circuit connected to the operating means, and separate circuit controlling means in said pilot circuit positioned for operation by each motor at each end of its stroke, said pilot circuit being connected to provide interlocking control of said control means whereby the bypassing of the pump is prevented until completion of movement of both motors.

10. In a hydraulic powertransmission systeml the'combination of a pump, a pair of oppositely movable piston and cylinder iluid motors, means connecting one end oi' each cylinder with the pumpfmeans connecting the other ends of the cylinders together in a secondary circuit for causcompletion of movement of both motors.

11. In a hydraulic power transmission system the combination ot a pump, a pair of oppositely movable piston and cylinder iluid motors, means connecting one end of each cylinder with the pump, means connecting the other ends of the cylinders together in a secondary circuit for caus-A ing movement o! one cylinder by uid discharged from the other cylinder and vice versa, control means including a spring-centered `four-way valve for selectively directing pressure uid from the pump to said one end of either cylinder or bypassing the pump, operating means for said con- .trol means, a pilot circuit connected to the operating means. and separate circuit controlling means in said pilot circuit positioned for operation by each motor at each end of its stroke, said pilot circuit being connected to provide interlocking control of said control means whereby thev bypassing of the p ump is prevented until completion of movement of both motors.

mais T.- HAaamo'roN., RUDOLF E. Escn. I 

